May 24
adminAlone at Home II Humidity, Mold, Mould
I have been working on a new data structure for storing the IR commands for the air conditioner. The best format is the decoded IR stream. Each time a button is pressed on the remote control two command are sent – the first decodes to 8 bytes and the second to 19 bytes. These 8 and 19 bytes are what will be stored in memory and just before it is sent it will be converted to the much longer stream driving the IR LEDs. I have already written functions to decode the raw IR stream to command bytes and back to IR stream. To save even more space I can store only one command and modify it by patching in the function (dry, heat), temperature and generate a new checksum. The task now will be to change the software to use the new data structure but keep the functionality as it is.
May 19
adminAlone at Home II Humidity, Mold, Mould
To control the air conditioner the system needs to send the same infrared commands a remote control does. To do this I first need to record all the the commands I may need into my computer. That is what I did today – 60 different commands. They are quite long and I need to decide how to store them effectively because the Jennic boards have limited memory. So far I have stored the commands in the format requiring the smallest and simplest program. With so many additional commands I will have to optimize.
May 17
adminAlone at Home II Humidity, Mold, Mould
The system is connected to a “slug” (Linksys NSLU2) which saves information in a database. The information sent by the system is basically measured data and a time stamp. This information is passed on by the “slug” over the internet to a remote computer. So far it has been a one way street, I cannot send commands to the system from a remote location. Now I need to remote control the system by setting a temperature so I can arrive to a heated house during the winter months. To achieve this I need to change the strategy I use to lower the relative humidity by heating the air. As an added bonus I believe the new strategy will work better and maybe use less energy too. As always the problem is to start ripping the software apart…
May 16
adminAlone at Home II Humidity, Mold, Mould
Because the Jennic hardware is so good and close to what I need, the project turned out to be a software project. The main purpose was to make something quick that would do the job for me in my house. I was debugging to the moment I closed the house for the winter and left. Fortunately I have a neighbour who is a good and capable man. He had to reset the system every now and then, but it actually worked much better than I dared to hope for. As always when write version 1 of a software project I learn a lot and when finished I know how I should have made it in the first place. To get rid of the expensive Zigbee network stack I used and to make a more robust and extensible system I decided to write version 2. This new version is currently running and with some improvements it is finished.
May 15
adminAlone at Home II Humidity, Mold, Mould
This is a project I have been working on for a couple of years now. It is a hardware and software project and the goal is to control mold growth in a vacant house. The house is in southern climate near the Mediterranean Sea and the average outdoor relative humidity is around 75%. I guess people with houses in e.g. Florida have the same problem. So far the hardware is an evaluation kit from Jennic extended with IR LEDs to control my Panasonic multisplit air-conditioner (3 indoor units) and a relay to control a fan. The goal is to keep the RH below 60%. During the summer the drying function of the air-conditioner is used. This is a double edged sword because drying the air also lowers the indoor temperature which again increases the RH. During the winter it is not possible to dry the air because this would be outside the operating parameters of the air-conditioner. Instead, the RH is lowered without drying by increasing the indoor temperature. The fan is used to help draw air into the house when the outdoor air is dryer than the indoor air. To complicate matters it is also necessary to keep an eye on what we put into the house. Everything natural (wool, cotton, wood, paper, etc.) are hygroscopic and when there is too much of it the possibility to control RH vanishes.
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